1. Field of the Invention
The present invention relates to a sampling rate converting system for converting a sampling rate of a video signal.
When a video signal is digitized and processed, a sampling frequency suitable for the TV system of the video signal should be used. For example, the NTSC system uses a sampling frequency of 4 fsc (=14.31818 MHz). The PAL system uses a sampling frequency of 4 fsc (=17.734475 MHz). The D2-MAC system usually uses a sampling frequency of 13.5 MHz. A down-converter of the MUSE-NTSC system uses a sampling frequency of 910 fH (=14.3325 MHz).
Thus, when a video signal processing system that can deal with video signals of various TV systems such as a world-wide type TV receiver, a large number of clock frequencies should be used.
Thus, such a video signal processing system converts a digital video signal into an analog video signal and then processes the analog video signal. Alternatively, the system converts a digital video signal into an analog video signal and then process the analog signal with a common sampling clock changed from the original sampling clock.
However, when an analog signal that has been converted from a digital signal is processed, many D/A converters and low-pass filters are required, thereby increasing the circuit scale. In addition, when a signal passes through many D/A converters and A/D converters, it tends to be deteriorated.